A dynamic random access memory (DRAM) is a type of integrated circuit device. High speed integrated circuit devices are often used, for example, in signal processing applications where conventional DRAM access speeds may be insufficient. High speed integrated circuit memory devices typically input and output data in-synchronization with an externally applied clock signal. For example, in a high speed integrated circuit memory device, data input and output operations may utilize an internal input and output clock signal. Recently, however, in order to achieve high speed operations and/or other advantages, other types of integrated circuit memory devices have been provided. Examples of such memory devices include a fast page mode DRAM, an extended data output (EDO) DRAM, a synchronous DRAM, a double data rate (DDR) DRAM, and a Rambus DRAM have been developed. The operating speed of the memory device is generally increased under various conditions with each of the above DRAMs by increasing the amount of input and output data (bandwidth) accessed per unit time.
Rambus DRAM technology is marketed by Rambus, Inc., Mountain View, Calif. The Rambus technology is described in U.S. Pat. No. 5,473,575 to Farmwald et al., U.S. Pat. No. 5,578,940 to Dillon et al., U.S. Pat. No. 5,606,717 to Farmwald et al. and U.S. Pat. No. 5,663,661 to Dillon et al. A device embodying the Rambus technology is also referred to as a "packet type integrated circuit device", because each integrated circuit receives data and addresses in packet units.
An example of a conventional Rambus DRAM integrated circuit device is illustrated in FIG. 1. As shown in FIG. 1, the Rambus memory device 101 includes first memory bank 181 and a second memory bank 182. It also includes a first input and output shift block 111, a second input and output shift block 112, an interface logic unit 121, a first input and output buffer 131, a second input and output buffer 132, a delay locked loop circuit 141 and a pad block 151.
In the conventional Rambus memory device 101, the first and second input and output buffers 131, 132 are located in the integrated circuit device substrate displaced (isolated) from the first and second input and output shift blocks 111, 112. Typically, the distance between each of the first and second input and output buffers 131, 132 and the first input and output shift block 111 is about 1000 micrometers (.mu.m) to 4000 .mu.m. The distance between each of the first and second input and output buffers 131, 132 and the second input and output shift block 112 is also typically about 1000 .mu.m to 4000 .mu.m. Accordingly, the output drivers (not shown) of the first and second input buffers included, respectively, in the first and second input and output buffers 131, 132 generally are designed so as to be able to transmit data from the respective first and second input buffers to the corresponding first and second input shift blocks included in the first and second input and output shift blocks 111, 112. The output drivers (not shown) of the first and second output shift blocks included in the first and second input and output shift blocks 111, 112 are also typically designed to have the capability to transmit data from the first and second output shift blocks to the corresponding first and second output buffers included in the first and second input and output buffers 131, 132.
As a result of the distances that the drivers are required to support, an undesirably large amount of power is typically consumed by the first and second input buffers and the first and second output shift blocks. In addition, as a result of the length of the data lines 171-174 used for data transmission between the first and second input and output buffers 131, 132 and the first and second input and output shift blocks 111, 112, data may be affected by noise.
In a further aspect of the conventional Rambus DRAM illustrated in FIG. 1, the delay locked loop circuit 141 generates an input control clock signal (sclk) and an output control clock signal (tclk). The input control clock signal (sclk) controls the input buffers included in the first and second input and output buffers 131, 132 and the input shift circuits included in the first and second input and output shift blocks 111, 112. The output control clock signal (tclk) controls the output buffers included in the first and second input and output buffers 131, 132 and the output shift circuits included in the first and second input and output shift blocks 111, 112. Respective clock lines 161-166 provide the input and output control clock signals (sclk) and (tclk) to the first and second input and output buffers 131, 132 and the first and second input and output shift blocks 111, 112 The clock lines 161-166 are placed in three pairs adjacent to the first and second input and output buffers 131, 132, the first input and output shift block 111, and the second input and output shift block 112 respectively.
As a result of the number of clock lines, the loads on the output drivers of the delay locked loop circuit 141 which drives the clock lines 161-166 are typically increased. This loading, in turn typically causes the delay locked loop circuit 141 to consume an increasing amount of power and may require a greater amount of area in the integrated circuit device. Correspondingly, the Rambus memory device 101 also may require a greater amount of area to implement resulting in a larger device.
As shown in FIG. 1, the clock lines 165 and 166 are installed between particular pads among a plurality of pads included in the pad block 151. As a result, a significant amount of noise may be generated in the input and output control clock signals (sclk) and (tclk), passing between the particular pads, due to interference caused by signals applied to the particular pads in the proximity of the clock lines 165, 166.
The data lines 173 and 174 for transmitting data between the first and second input and output buffers 131, 132 and the second input and output shift block 112 are positioned with a portion passing through the pad block 151 as a result of the placement of the pad block 151 between the circuits being connected by the data lines 173, 174. This layout may also contribute to increasing the size of the Rambus memory device. In addition, as with the clock signals, signals transmitted via the data lines 173, 174 may be subjected to interference from signals applied to pads included in the pad block 151 in the vicinity of the data lines 173, 174. This noise could lead to instability on the data lines 173, 174.
Accordingly, there is a need for improved integrated circuit memory devices such as Rambus DRAMs.